Why did the U.S. become involved in the politics of Southeast Asia. and how did this involvement impact the U.S. political climate of the 1950's.

Answer 1

It was called the Domino Theory. Check these sites.

http://www.spartacus.schoolnet.co.uk/COLDdomino.htm

http://en.wikipedia.org/wiki/1950s

Answer 2

Read carefully:

http://www.u-s-history.com/pages/h1888.html